Multiple conditions in IF

Shell Programming and Scripting
1

Fellas,

Am new to unix os/ and here the situation , I am trying to write multiple condition statement inside if but it throws me a error

here is my piece of code ,

if [ [ $file1 ne " " ] ] && [ [ $file2 ne " " ] ] && [[ $file3 ne " " ] ]
then 
commands
fi

error : line 15 : [ : missing `]`

can someone please advise me how to fix it

2

Hello xeccc5z,

Welcome to forums, please use code tags for commands/codes/Inputs which you are using into your posts as per forum rules. Could you please try following.

if [[ -z $file1 && -z $file2 && -z $file3 ]]
then 
commands
fi

You could go through manual entry for test too.

Thanks,
R. Singh

3

RavinderSingh13

Thanks for your response and since I am new this I may missed out the rules and i will do it from now on

And my query is I am passing file names as command line arguments and my condition should alert the user if he fails to pass the parameter

am saving those parameters in a variable called file1, file2 and file3

i believe [ -z file ] will check whether file is a zero size file or not , correct me if iam wrong

4

Hello xeccc5z,

You welcome, you could hit THANKS button at left side of any post for any useful post to a person. Yes, for NULL values it should work.

Thanks,
R. Singh

1 Like
5

Ravinder,

As i said am passing the file names as command line argument and saving them in variables as file1,file2,file3. When user fails to pass anyone of the arguemnt it should display error message and quit from the script hence i would like to for if condition and checks those file1,file2,file3 values are not empty , how could i right that

6

If you're checking the first 3 positional parameters instead of the variables you specified before, change:

if [[ -z $file1 && -z $file2 && -z $file3 ]]

in Ravinder's suggestions to:

if [[ -z $1 && -z $2 && -z $3 ]]

but, of course, all of this assumes that you're using a shell that recognizes [[ expression ]] syntax.

1 Like
7

The -z test checks for a string's zero length, e.g. if the file name was given. To check for a file's contents being zero or not, use the -s test.

1 Like
8

Why not use bash's special parameter # ?
# Expands to the number of positional parameters in decimal.
Example:

#!/bin/bash

if [[ "$#" -ne "3" ]]; then
 echo "Need 3 files, you supplied $#, please try again."
 exit 1
fi

set -x
file1=$1
file2=$2
file3=$3
set +x

Test:

$ ./script
Need 3 files, you supplied 0, please try again.
$ ./script foo
Need 3 files, you supplied 1, please try again.
$ ./script foo bar
Need 3 files, you supplied 2, please try again.
$ ./script foo bar baz
+ file1=foo
+ file2=bar
+ file3=baz
+ set +x
$